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Date:      Wed, 7 Mar 2001 02:44:56 -0800
From:      Kris Kennaway <kris@obsecurity.org>
To:        Jordan Hubbard <jkh@osd.bsdi.com>
Cc:        kris@obsecurity.org, ohartman@klima.physik.uni-mainz.de, antony@abacus.co.uk, freebsd-stable@FreeBSD.ORG
Subject:   Re: ARCH flag in new make.conf
Message-ID:  <20010307024456.A37349@mollari.cthul.hu>
In-Reply-To: <20010307020500X.jkh@osd.bsdi.com>; from jkh@osd.bsdi.com on Wed, Mar 07, 2001 at 02:05:00AM -0800
References:  <20010307012454.A14664@mollari.cthul.hu> <20010307014323M.jkh@osd.bsdi.com> <20010307015036.A36721@mollari.cthul.hu> <20010307020500X.jkh@osd.bsdi.com>

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On Wed, Mar 07, 2001 at 02:05:00AM -0800, Jordan Hubbard wrote:
> From: Kris Kennaway <kris@obsecurity.org>
> Subject: Re: ARCH flag in new make.conf
> Date: Wed, 7 Mar 2001 01:50:37 -0800
>=20
> > I can be confident it is not a dangerous option, having never seen
> > code failure caused by it desipite extensive use for a long time.
>=20
> Well, first off you're not even setting it to the same value he
> was. :)

Yes I am:

     While picking a specific CPU TYPE will schedule things
     appropriately for that particular chip, the compiler will not
     generate any code that does not run on the i386 without the
     `-march=3DCPU TYPE' option being used.  `i586' is equivalent to
     `pentium' and `i686' is equivalent to `pentiumpro'.  `k6' is the
     AMD chip as opposed to the Intel ones.

i686 =3D=3D pentiumpro

> > This is not the case with optimizations generally accepted to be
> > dangerous (like -O2) from which I have seen many failures from on my
>=20
> Grrr.  Please stop raising -O2 - it's a total red herring and I've
> never implied any kind of causual link between the overall
> optimization level and the architecture specific optimizations. :( I
> don't know why everybody keeps bringing it up like it was garlic for
> warding off vampires or something.

I was trying to justify to myself why you thought this was such a bad
thing, I thought perhaps you were thinking of a similarity with -O2.

> > own systems.  Given the number of people who use -march with no ill
> > effects the 50/50 estimate is not very accurate.
>=20
> Ahem, do we actually know that number?  I can't help but feel like
> we're both swinging in the dark here, the only difference being that
> I'm arguing about avoiding a serious failure and you're arguing about
> avoiding a serious warning. :)

This whole thing came totally out of the blue for me, I would have
appreciated a bit of discussion before unilaterally declaring the
project I've been working on "bad for users".

Kris


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